not detecting 3rd monitor

[kcosyns]

I have a laptop ( MSI PS63 modern 8M, with the  UHD graphics 620 driver ) connected to 2 external displays using a dell dock station (all drivers are up to date).The displays are each connected with HDMI cables to the docking station and the laptop via a USB C cable. 

Only one external display is recognized (see screenshots in attach), the 2nd external dispaly is not. Sometimes I manage to makeit work by just slecting it and hit "extend to this display" but most of the times the display is just not detected.

How to solve this? When I connect my Dell work laptop I don't have this issue. 

[MUC]

MSI Prestige Series Video Output Information (slide 21):

X = not supported

*1: Type C USB port supports only data transmission and the display out, no Thunderbolt function.